The Celtic playmaker hasn't reached the heights of last season just yet.
The 24-year-old was voted Celtic's Player of the Year last season but is yet to hit those heights this campaign.
And Deila admits it is up to him to get the best out of his playmaker, who has suffered from injury problems over the last few months.
The Celtic boss told reporters: "Stefan has had troubles with his back since pre-season. He has played but has had issues. He also had a bad knock against Fenerbahce on his neck. There is more to come though. You know with Stefan that you get 100 per cent hard work all the time.
"In my eyes he is a winner. When you see him for Norway, he is the leader in the team. He dictates what’s going on. He is 24-years-old and has a long career ahead but when you play 70 games you can have dips.
"It’s my task to get him back to the level he can be as quickly as possible."
Johansen's lack of form hasn't gone unnoticed by Celtic fans, who were pleased when Deila left him out during the 6-0 win over Dundee, with the result justifying the call.
Naturally, though, there is no doubt the Norwegian is a top talent - how else would he have won himself the Player of the Year award last term?
As Deila says, it's up to the Celtic staff to get the best out of the 24-year-old while taking his injury problems into account.
It'll be a return to Norway for Deila and Johansen on Thursday, when they travel to Molde in the Europa League during a game Celtic must aim for the win after two draws in their last two European fixtures.